Another week another severe storm - this one with a central pressure of 968hpa over Christchurch tomorrow afternoon! Places like Dunedin and Timaru could receive between 120-160mm in a 12 hour period along with severe gales and over a metre of snow above 700m. This one is a doozy...

SEVERE WEATHER WARNING.

ISSUED BY MetService AT 11:44 am 20-Jul-2017Heavy rain for Bay of Plenty, Canterbury and eastern Otago. Also, strong winds for Auckland, Bay of Plenty and Gisborne.NOTE: THIS IS AN UPDATE TO INCREASE THE RAINFALL AMOUNTS FOR SOUTH CANTERBURY, NORTH OTAGO AND DUNEDIN.

A large complex low pressure system is expected to move over the country today and slowly move east during Friday and Saturday. An associated front crosses the North Island, bringing a period of severe gale northeasterlies and a burst of heavy rain to northern parts of the Island. The strongest winds are expected in Bay of Plenty and Gisborne where northeast gusts could reach 120 km/h in exposed places. Heavy rain is expected in Bay of Plenty and Rotorua from this afternoon to overnight tonight, and 100mm of rain could accumulate in 12 hours.

Rain is also expected to become heavy over eastern districts of the South Island during Friday and continue into Saturday as the complex low pressure system moves east. The heaviest falls are expected in Canterbury south of the Rakaia River and eastern Otago where up to 200mm of rain could accumulate, with snow lowering to 800 metres about the Canterbury High Country and 600 metres in Otago during Friday evening.

This is a significant weather event and the combination of heavy rain and strong winds is expected to cause widespread disruption to transport, localised flooding and slips. Winds of this strength can cause damage to trees, powerlines, unsecured roofs and structures, and make driving hazardous. Also in the South Island, wind chill due to cold temperatures and strong winds could cause stress to livestock.

Note, large south to southeast waves may cause coastal inundation along south Canterbury and Otago coasts during Friday and Saturday.

HEAVY RAIN WARNINGAREA/S AFFECTEDBay of Plenty and RotoruaFORECASTRain is expected to become heavy this afternoon, and ease overnight tonight.

In the 12 hours from 2pm this afternoon to 2am Friday morning, expect 90 to 100mm of rain to accumulate. Peak intensities of 20 to 30mm per hour.

AREA/S AFFECTEDCanterbury north of the Rakaia RiverFORECASTRain is expected to become heavy Friday morning and ease overnight Friday.

In the 20 hour period from 6am Friday to 2am Saturday, expect 120 to 160mm of rain about the Foothills and ranges and 80 to 100mm towards the coast. Peak intensities of 15 to 20mm per hour. However, above 800 metres, rain turns to snow from Friday evening.

Some extreme weather today and tomorrow for the lower North Island and the top half of the South Island with the passing of ex TC Gita, will be some major flood and storm surge issues by this time tomorrow morning:

Cyclone Gita, currently located over the Tasman Sea, is forecast to track southeastwards and cross central New Zealand late today and early Wednesday.

Note that the Watches for heavy rain for Christchurch, the Banks Peninsula and North Otago have been upgraded to full Warnings.

The passage of Gita is expected to bring a period of high-impact severe weather to central New Zealand. Heavy rain will cause slips, rapidly rising streams and rivers, and flooding. Severe gales with damaging gusts are expected, so people are advised to secure property and items that may be blown away by strong winds. There is also the potential for coastal inundation with high tide overnight Tuesday and before dawn on Wednesday, due to the combination of tides, low air-pressure, strong onshore winds and large waves in excess of 6 metres in some places. For the North Island, coastal areas from Raglan southwards to southern Wairarapa are most at risk. For the South Island, the risk of coastal inundation is greatest for areas from Buller and North Canterbury northwards.

Heavy Rain WarningHeavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.Area: Nelson and BullerValid: 10 hours from 11:00am to 9:00pm TuesdayForecast: In addition to rain that has already accumulated expect a further 100 to 150mm of rain to in Nelson west of Motueka, and 70 to 100mm elsewhere. Peak intensities of 20 to 30mm/hr possible.

Area: Marlborough including the Kaikoura CoastValid: 11 hours from 11:00am to 10:00pm TuesdayForecast: In addition to rain that has already accumulated expect a further 100 to 150mm of rain about higher ground, and 70 to 120mm elsewhere. Peak intensities of 20 to 30mm/hr possible.

Area: Wellington and Kapiti CoastValid: 3 hours from 11:00am to 2:00pm TuesdayForecast: Expect a further 30 to 40mm in addition to the rain that has already accumulated. Peak intensities 10 to 15mm per hour. Further lighter rain is expected for the remainder of today.

Area: Canterbury including Christchurch and the Banks Peninsula. The ranges of Westland.Valid: 24 hours from 11:00am Tuesday to 11:00am WednesdayForecast: In addition to rain that has already accumulated expect a further 90 to 150mm of rain to accumulate during this period about Canterbury High Country, and 70 to 100mm elsewhere. Peak intensities of 20 to 30mm/hr possible about Canterbury High Country.

Area: North Otago.Valid: 22 hours from 1:00pm Tuesday to 11:00am WednesdayForecast: Expect 60 to 90mm of rain to accumulate. Peak intensities of 10 to 15mm/hr.

Strong Wind WarningStrong wind gusts could damage trees, powerlines and unsecured structures. Driving may be hazardous, especially for high-sided vehicles and motorcycles.Area: Taranaki, Taihape, WhanganuiValid: 10 hours from 3:00pm Tuesday to 1:00am WednesdayForecast: Severe gale north to northwest winds gusting 120 km/h in exposed parts of North Taranaki, but damaging gusts of 140 km/h in exposed parts of South Taranaki, Whanganui and Taihape.

Area: Westland and the Canterbury High Country near the AlpsValid: 11 hours from 12:00pm to 11:00pm TuesdayForecast: Severe gale southeast winds with damaging gusts of 150 km/h possible in exposed places.

Goodluck Pete. I was keeping tabs on Gita till it started tracking SE. I think the bullseye is further south in NZ than first thought. Wellington I think it was. Can't be entirely precise with these things I guess. Wow what a dump at Mt Hutt

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If you can't change something, there is only one option. Adapt!

First really good cold snap heading New Zealandís way on Tuesday and Wednesday with heavy snow above 400m for Canterbury and 500m for Otago. For early April this is a little unusual but not unheard of.

On Monday, a deepening low is expected to be approaching central New Zealand from the Tasman Sea. Meanwhile a cold front should move up the South Island during the day. The low is expected to cross over the North Island during Tuesday, allowing strong cold southerlies to spread over the entire country.

The combination of these features is expected to bring strong to gale force winds, heavy rain and thunderstorms to many places over first half of next week. Significant snowfalls are likely about the higher ground of both Islands, with lesser amounts down to around 400 metres in the South Island and 700 metres in the North Island.

During Monday and Tuesday there is low confidence that snowfalls above 500 metres in Southland and Otago will be enough to warrant a warning. On Tuesday and Wednesday there is moderate confidence that snowfall accumulations above 400 metres in Canterbury, Marlborough and Nelson will need a warning. About Tongariro National Park there is low confidence that a warning for heavy snow above 900 metres will be needed on Wednesday.

There is low confidence that heavy rain about Buller, Nelson, the Marlborough Sounds,and the North Island from southern Waikato to Kapiti, including Taupo and Taihape on Tuesday will be enough for a warning.

During Tuesday and Wednesday, severe southwest to southeast gales could affect most of the North Island and eastern areas of the South Island. Currently there is moderate confidence that a warning will be required for northern Marlborough and all North Island areas except Gisborne, Hawkes Bay and the Tararua District. There is low confidence that a wind warning will be needed for the eastern South Island during Tuesday and Wednesday and for Gisborne, Hawkes Bay and Tararua district on Wednesday and Thursday.

Also, large southerly waves are forecast to affect southern and eastern coasts of both Islands on Tuesday and Wednesday, while large southwesterly waves may affect the west coast of the North Island from Taranaki northwards on Wednesday.

During Wednesday a narrow ridge should move onto the South Island, easing weather conditions there. The ridge moves towards the North Island on Thursday while another low approaches the South Island bringing rain to the west of the Island. There is low confidence that warning amounts of rain will fall in Fiordland and southern Westland on Thursday.